This active landfill is currently owned and operated by the Rhode Island Resource Recovery Corporation - RIRRC (formerly the Rhode Island Solid Waste Management Corporation) and receives approximately 85 percent of Rhode Island's solid waste. The landfill is currently comprised of five areas. One of these areas, a 121-acre area (sometimes called the Phase 1 area), was used prior to 1980 for the disposal of municipal and hazardous waste. The other four areas (Phases 2, 3, 4 and 5) have been used to dispose of municipal solid waste. Landfilling in the Phase 2 and 3 areas stopped in July 2003. There are also plans for additional expansions beyond the Phase 5 area.

Located within the 121-acre, Phase 1 area is an approximately 1/2 acre area where a minimum of 1.5 million gallons of documented hazardous wastes were disposed of between 1976 and 1979. Within this 1/2 acre hazardous waste area, bulk liquid waste was dumped into trenches that had previously been excavated into bedrock. The wastes disposed of in this area included latex waste, acid waste, corrosive waste, water soluble oils and waste solvents, including methylene chloride, toluene, 1,1,1-trichlorethane and tetrachloroethylene (PCE). EPA believes that, prior to 1976, a large quantity of non manifested liquid hazardous waste was also disposed of in this 1/2 acre area. In 1982, the owner complied with a State order to close the areas that had received hazardous material. These areas have been excavated, backfilled, and capped to minimize further contamination of the groundwater and surface water, and revegetated as part of the closure plan.Approximately 4,000 people live within 3 miles of the site. The bedrock aquifer underlying the site has been contaminated.

On-site groundwater is contaminated with volatile organic compounds (VOCs) such as benzene, chlorobenzene, toluene, vinyl chloride, methyl ethyl ketone, bis(2-ethylhexyl)phthalate and 1,2-dichlorobenzene, and heavy metals including arsenic, beryllium, cadmium, lead, manganese, and vanadium. Adjacent surface waters, sediments, and wetlands have also been affected by low levels of contamination. The EPA has determined that the public is not at immediate risk from contaminants emanating from the site. Potentially affected residents and businesses are supplied with drinking water from a public water supply system that ensures human health is fully protected.

The current owner installed a landfill gas collection and combustion system in the 121-acre, Phase I area which is used to generate electricity, as well as public water supply lines in the area surrounding the Central Landfill. The current owner also purchased all residential land within 1,000 feet of the landfill, and offered to purchase all residential property up to 2,000 feet surrounding the landfill. Most residential owners within the 1,000 to 2,000 foot zone agreed to sell their property.

On-Site Contamination

In 1987, the owner/operator began an investigation into the nature and extent of site contamination. The study identified the sources of contamination and, in June 1994,an OU1 Record of Decision (ROD) was signed which selected a cleanup plan to control the identified sources of contamination. The cleanup plan included capping the 121-acre, Phase 1 area; extracting and treating groundwater in the most highly contaminated 1/2 acre area within the 121-acre, Phase I area; establishing institutional controls; and conducting a detailed evaluation of the existing landfill gas collection and combustion system. The cleanup plan was completed in September 2006. EPA Region 1 signed a Preliminary Close-Out Report in September 2006.

Off-Site Contamination

In 1994, the owner/operator began an investigation to evaluate groundwater contamination beyond the 612-acre Central Landfill facility boundary including within nearby surface waters, soil, and sediments beyond the 154 acre Phase 1, 2 and 3 areas. A second Record of Decision (ROD) was signed in September 2002. The September 2002 ROD called for no further remedial action beyond that already required by the 1994 ROD.

Enforcement Highlights

In 1987, the owner of the landfill entered into a Consent Order with the EPA to conduct a study of site contamination. The on-site cleanup plan required by the 1994 RODand discussed above is being performed by the current owner (RIRRC) under a October 1996 Consent Decree.
A September 2005 Explanation of Significant Difference (ESD) to the June 2004 OU1 ROD removed the requirement to treat the extracted hot spot groundwater using an on-site Ultraviolet/Chemical Oxidation system. The extracted groundwater is now being conveyed to an on-site leachate pre-treatment system instead. See Current Site Status below for additional information. The September 2005 ESD also revised the OU1 performance standard for arsenic in groundwater from 50 ppb down to 10 ppb to reflect the national change to the MCL for arsenic.

The installation of the landfill gas collection and combustion system and public water supply lines, and the purchase of residential property around the landfill have reduced the threat to public health. The Department of Justice (DOJ) entered a Consent Decree with the RI District Court on October 2, 1996.

Construction of the RCRA C cap started with the placement of controlled fill in July 1997 and the approximately 89-acre cap construction project was completed in November 2005; bringing the total OU1 cap area to 121-acres (which includes the 32-acres of pre-existing RIDEM approved cap). A pre-final inspection was performed for the entire capped area in November 2005.

Construction of the hot spot hydraulic containment system started with the installation of a groundwater extraction well in July 2003 and construction of the final conveyance pipeline to the existing Central Landfill leachate pre-treatment system (see paragraph below) was completed in September 2006. A pre-final inspection for the hot spot hydraulic containment system was performed on September 21, 2006.

As part of its expansion efforts (now spanning five phases), RIRRC constructed a leachate pretreatment system that collects and treats leachate from these expansion phases of the landfill. The leachate pretreatment system consists of chemical precipitation to remove metals before being discharged to the Cranston Waste Water Treatment Plant. Groundwater is currently being extracted from the hot spot area of the landfill and discharged directly to this leachate pretreatment system.

Deed restrictions and a long-term groundwater, surface water and air monitoring program are in place. As part of the OU1 remedy, the RIRRC filed a Declaration of Covenants and Environmental Protection/Conservation Easements on property it owns at the 612-acre Facility. This Covenant prohibits the use of groundwater except for remediation purposes, prohibits the installation of groundwater wells or the use of existing groundwater wells and prohibits the alteration of the groundwater flow in any way. Further, the Town of Johnston adopted a Town Ordinance that, among other things, prohibits the use of groundwater wells and prohibits the Town's building inspector from issuing permits for the construction of groundwater wells in any location where access to Town public water is available and where the well or proposed well is located in certain described areas.

The evaluation of the existing landfill gas collection and combustion system was completed in 2005. The evaluation concluded that the gas collection and combustion system is in compliance with state and federal regulations and the air risk assessment performed as part of this evaluation concluded that the air emissions for the combustion facility presented no risks to human health. Access to the site is controlled by a combination of fencing and on-site security.

The second Five-Year Review (FYR) was issued in September 2008. This FYR found that concentrations of lead in Upper Simmons Reservoir sediment during the last three years exceeded the consensus based Threshold Effects Concentration and Probable Effects Concentration sediment quality guidelines for lead and therefore present a long-term ecological risk. The FYR also found that the detection limits for metals in surface water need to be lowered to verify that metals at the Site are not presenting a long-term ecological risk. The FYR concluded that: the remedy is protective of human health; the remedy is protective of the environment in the short-term; and the remedy may not be protective of the environment in the long-term since the sediment lead levels in the Upper Simmons Reservoir are currently presenting a long-term ecological risk. The FYR report is available at both site repositories listed below and via this website.

To date the detection limits for metals in surface water have been modified and a study is underway to assess lead concentrations in Site sediment and surface water compared to concentrations found in the Upper Simmons Reservoir.